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A267233 Number of length-4 0..n arrays with no following elements greater than or equal to the first repeated value. 1
6, 47, 176, 470, 1030, 1981, 3472, 5676, 8790, 13035, 18656, 25922, 35126, 46585, 60640, 77656, 98022, 122151, 150480, 183470, 221606, 265397, 315376, 372100, 436150, 508131, 588672, 678426, 778070, 888305, 1009856, 1143472, 1289926 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A267232.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..210

FORMULA

Empirical: a(n) = n^4 + (17/6)*n^3 + 2*n^2 + (1/6)*n.

Conjectures from Colin Barker, Feb 05 2018: (Start)

G.f.: x*(6 + 17*x + x^2) / (1 - x)^5.

a(n) = 5*a(n-1) - 10*a(n-2) + 10*a(n-3) - 5*a(n-4) + a(n-5) for n>5.

(End)

EXAMPLE

Some solutions for n=6:

..4....5....2....2....0....4....4....5....0....4....3....2....0....4....0....3

..3....3....4....0....5....2....0....6....3....5....4....4....3....3....2....6

..1....3....2....5....5....3....1....2....5....5....2....1....0....2....4....4

..4....0....6....4....4....1....4....1....4....3....3....3....6....4....2....6

CROSSREFS

Cf. A267232.

Sequence in context: A256160 A184725 A232495 * A027012 A160609 A267203

Adjacent sequences:  A267230 A267231 A267232 * A267234 A267235 A267236

KEYWORD

nonn

AUTHOR

R. H. Hardin, Jan 12 2016

STATUS

approved

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Last modified May 16 23:46 EDT 2021. Contains 343957 sequences. (Running on oeis4.)